Astyanax goyanensis (Miranda-Ribeiro, 1944) Bertaco & Carvalho & Jerep, 2010

Bertaco, Vinicius A., Carvalho, Fernando R. & Jerep, Fernando C., 2010, Astyanax goyanensis (Miranda-Ribeiro, 1944), new combination and Astyanax courensis, new species (Ostariophysi: Characiformes): two Characidae from the upper rio Tocantins basin, Central Brazil, Neotropical Ichthyology 8 (2), pp. 265-275 : 266-269

Astyanax goyanensis (Miranda-Ribeiro, 1944) , new combination

Figs. 1-2

Astyanacinus goyanensis Miranda-Ribeiro, 1944:1-2 (original description, type-locality: “Rio do Couro, Veadeiros, estado de Goiaz”; picture of holotype). - Fowler, 1948:34 (distribution). - Lima et al., 2003:108 (maximum length and distribution). - Lima et al., 2007:44 (type-locality and distribution).

Material examined. MNRJ 4129 , holotype, female, 82.2 mm SL, rio dos Couros, Chapada dos Veadeiros, Goiás State, Brazil, 1929 , R. Pfrimmer . MNRJ 2843 , paratypes, 5 of 7, 59.4-84.8 mm SL, collected with the holotype . MCP 44402, topotypes, 20, 26.9-63.9 mm SL , UFRGS 11291 , 80 , 5 c&s, topotypes, 18.5-79.9 mm SL, small tributary of rio dos Couros at Parque Portal da Chapada , affluent of rio Tocantinzinho, upper rio Tocantins basin, 1135 m a.s.l, Alto Paraíso de Goiás, Goiás State, Brazil, 14º10’13”S 47º36’35”W, 10 Sep 2009 , V. A. Bertaco, F . R. Carvalho & G. Frainer .

Additional material. Goiás State, Brazil, upper rio Tocantins basin, rio dos Couros basin. MCP 23937, 6 , 22.1-61.5 mm SL, córrego Capão da Guabiroba tributary of rio dos Couros, Alto Paraíso de Goiás, 14º07’43”S 47º38’27”W, 4 Aug 1996, W. R. Koch, P. Milani & K. M. Grosser. UFRGS 9905 , 19 , 27.8-55.6 mm SL, córrego Rita Maria between Cavalcante and Minaçú, rio Paranã basin, Cavalcante , 13º45’16”S 47º27’18”W, 25 May 2008, F. C. Jerep & T. P. Carvalho. UFRGS 9935 , 31 , 2 c&s, 17.1-50.2 mm SL, córrego on road GO- 239 between Alto Paraíso de Goiás and Parque Nacional da Chapada dos Veadeiros, Alto Paraíso de Goiás, 14º08’24”S 47º39’36”W, 25 May 2008, F. C. Jerep & T. P. Carvalho. UFRGS 9960 , 12 , 22.8- 82.4 mm SL, rio das Cobras between Alto Paraíso de Goiás and Parque Nacional da Chapada dos Veadeiros, 14º09’39”S 47º37’55”W, 25 May 2008, F. C. Jerep & T. P. Carvalho .

Diagnosis. Astyanax goyanensis belongs to the A. scabripinnis species complex and is distinguished from all species of this complex by the total number of pelvic-fin rays (7 vs. 8), except from A. brachypterygium Bertaco & Malabarba , A. ita Almirón, Azpelicueta & Casciotta , and A. obscurus (Hensel) , Bertaco & Lucena (2010). It differs from A. brachypterygium by caudal peduncle length (14.1-18.5% SL, mean = 16.1 vs. 11.9-14.4, mean = 13.0), by the number of caudal-peduncle scales (14 vs. 16), and by the number of cusps of the premaxillary inner series and the larger dentary teeth (4-5 vs. 5-7); from A. ita by the number of branched anal-fin rays (13-16 vs. 20-24), number of humeral spots (2 vs. 1), and by the orbital diameter (20.2-33.2% HL, mean = 27.4 vs. 38.6- 42.0, mean = 40.2); and from A. obscurus by the number of maxillary teeth (2-5 vs. 1), number of lateral line scales (35-37, mean = 36 vs. 37-39, mean = 38), and by the number of branched anal-fin rays (13-16, mean = 14.7 vs. 16-21, mean = 18.3). Furthermore, the lower number of the branched anal-fin rays in A. goyanensis distinguish it from its congeners of the species complex, except from A. brachypterygium , A. cremnobates Bertaco & Malabarba , A. laticeps (Cope) , A. intermedius Eigenmann , A. jenynsii (Steindachner) , A. jordanensis Alcaraz, Pavanelli & Bertaco , A. microschemos Bertaco & Lucena , A. totae Haluch & Abilhoa , and A. varzeae Abilhoa & Duboc. It differs from most these species by the number of humeral spot (2 vs. 1), except A. brachypterygium , A. cremnobates , and A. varzeae . From these three species it differs by the number of cups in the premaxillary and dentary teeth (5-7 vs. 3-5), and by the caudal-peduncle length (14.1- 18.5% SL, mean = 16.1 vs. 11.9-14.4, mean = 13.0, 11.0-14.9, mean = 13.1, 10.5-13.9, mean = 12.4, respectively), and additionally from A. varzeae by the number of lateral line scales (35-37, mean = 36 vs. 37-42, mean = 39).

Description. Morphometric data summarized in Table 1. Body compressed and elongate; greatest body depth usually immediately anterior to dorsal-fin origin. Dorsal profile of head between vertical through posterior nostril and tip of supraoccipital spine straight or slightly convex. Profile of body convex from tip of supraocciptal spine to base of last dorsalfin ray, and slightly concave from that point to adipose-fin origin. Ventral profile of head convex. Ventral profile of body slightly convex from pectoral-fin insertion to anal-fin origin. Body profile along anal-fin base posterodorsally slanted. Caudal peduncle elongate and nearly straight to slightly concave along both dorsal and ventral margins.

Snout rounded from margin of upper lip to vertical through anterior nostrils. Head relatively small (one third of SL). Mouth terminal, lower jaw projecting slightly more than upper jaw. Maxilla extending posteriorly to vertical through anterior half of orbit, slightly curved, and aligned at angle of approximately 45 degrees relative to longitudinal body axis. Maxilla slightly widened anteroposteriorly.

Premaxilla with two tooth rows: outer row with three to five tri- to pentacuspid teeth, central cusp longest. Five teeth in inner premaxillary row; teeth gradually decreasing in length from first towards fourth teeth with last tooth distinctly smaller: teeth with five to seven cusps with central cusp twice as long and broad as other cusps. Maxilla with two to five (five only in the holotype and one paratype) teeth with three to five cusps; central cusp longest. Three to four anteriormost dentary teeth larger, with five or seven cusps, followed by one medium-sized tooth with three to five cusps, and five to seven teeth with one to three cusps. Central cusp in all teeth two to three times as long and broad as other cusps. All cusp tips slightly curved posteriorly towards oral cavity ( Fig. 2 ).

Dorsal-fin rays ii,9 (holotype with ii,8; three paratypes with i,9, seven topotypes with i,9, and ii, 8 in two c&s specimens, n = 32); first unbranched ray approximately half length of second ray. Distal margin of dorsal fin nearly straight or slightly convex. Dorsal-fin origin anterior at middle of SL. Adipose-fin origin approximately at vertical through insertion of base of last anal-fin ray. Anal-fin rays ii-v, 13-16 (holotype with anal incomplete, 13, mean = 14.7, n = 32). First unbranched ray apparent only in c&s specimens. Anal-fin profile nearly straight in males, and smoothly concave in females. Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Anal-fin rays of males bearing one pair of small bony hooks along posterolateral border of each segment of lepidotrichia, usually along last unbranched ray to eighth anterior branched rays. Hooks more numerous along second through fifth branched ray, and usually located along posteriormost branch and distal 1/2 to 2/3 of each ray.

Pectoral-fin rays i,10-13 (mean = 12.0, n = 32). Tip of pectoral fin reaching pelvic-fin insertion in males and not reaching that insertion in females. Pelvic-fin rays i,6 (n = 32). Pelvic-fin origin slightly anterior to vertical through dorsal-fin origin. Tip of pelvic fin reaching anal-fin origin in males, falling short of that point in females. Caudal fin forked and unscaled, lobes similar in size, with 19 principal rays. Dorsal procurrent rays 11-14, and ventral procurrent rays 10-12 (n = 7).

Lateral line complete with 35-37 scales (mean = 36.0, n = 32). Scale rows between dorsal-fin origin and lateral line 6-7 (mean = 6.1, n = 32); 4-5 scale rows between lateral line and pelvic-fin origin (mean = 4.5, n = 32). Predorsal scales 11-14 (mean = 12.5, n = 32) usually arranged in regular series. Scale rows around caudal peduncle 14 (n = 32). Axillary scale on pelvic-fin origin extends posteriorly covering 2-3 scales. Scale sheath along anal-fin base 5-12 scales, in single series, covering base of anteriormost rays (n = 30).

Precaudal vertebrae 17-18; caudal vertebrae 17-18; total vertebrae 35 (n = 7). Supraneurals 5-7 (n = 7). Upper branch of gill-rakers 7-8, lower branch 11-12 (n = 7).

Color in alcohol. General body color yellowish-brown. Dark chromatophores scattered on lateral portion of head, more densely concentrated on snout and anterior border of eye. Lateral portion of body with scales bordered with dark pigment, forming slightly reticulate pattern.Body with black, pigmented, midlateral stripe extending from humeral region to base of middle caudal fin; faint dark pigmentation present on middle caudal-fin rays. Midlateral body stripe expanded dorsally and ventrally to caudalfin base, forming small caudal spot.Two humeral spots: anterior spot conspicuous, vertically elongate, with superior portion wider, located over second to fourth vertical series of scales, extending over 2 to 3 horizontal series of scales above lateral line; and inferior portion of spot narrow, and extending over 1 to 2 horizontal series of scales below lateral line; posterior humeral spot diffuse, not ventrally surpassing lateral-line, extending over 2 to 3 horizontal series and 2 to 3 vertical series of scales. Region between spots pale. Fins with dispersed dark chromatophores ( Fig. 1b ). Specimens retained orange and yellowish pigment on all fins after several days fixation in formalin.

Color in life. The specimens immediately after capture presented overall golden body coloration. Fins yellowish-orange to red. Humeral spots faint black, and midlateral stripe and caudalpeduncle spot less conspicuous than after preservation. Caudalfin middle rays black ( Fig. 1b ).

Sexual dimorphism. Males of Astyanax goyanensis are easily recognized by the presence of small bony hooks on the anal-fin rays (see Description).Also, males and females differ by anal-fin shape, which is nearly straight in males and concave in females.

Gill glands (Burns & Weitzman, 1996) were not found macroscopically on first gill arch in either males or females.

Distribution. Astyanax goyanensis is known from tributaries of the rio dos Couros, affluent of rio Tocantinzinho, and rio Paranã basin, upper rio Tocantins basin, Chapada dos Veadeiros, Goiás, Brazil ( Fig. 3 ).

Ecological notes. The collection locality is around 1135 m above sea level. The rio dos Couros in that point has moderate riparian vegetation and it is typically between 10 and 15 m wide, and 1.5 m deep. Although presenting some rapids, the water is clear. The substrate is constituted by stones, rocks, and some stretches with mud. A natural 10 m high waterfall named Cachoeira São Bento is located downriver.All topotypes were collected on the stretch downstream from the waterfall in a small stream draining directly into the river (about 100 m from the channel river). The stream is about 0.8 m deep and 6 m wide, has transparent water with moderate vegetation covering the channel (trees and shrubs), and bottom with small stones, submerged logs and roots ( Fig. 4b ). No other fish species was collected with A. goyanensis in the stream. The rio dos Couros has several waterfalls, some with about 100 m height (Cachoeira de São Vicente and Catarata dos Couros). Stomach contents of five specimens contained fragments of allochthonous insect, fish scales, and vegetal organic matter (leaf parts). The stomachs were not full.

Figures

Fig. 1. Astyanax goyanensis. (a) MNRJ 4129, holotype, female, 89.2 mm SL; rio dos Couros, Chapada dos Veadeiros, Goiás State, Brazil (anal-fin incomplete); (b) UFRGS 11291, topotype, male, 56.7 mm SL; small stream tributary of rio dos Couros at Parque Portal da Chapada, tributary of rio Tocantinzinho, upper rio Tocantins basin, Alto Paraíso de Goiás, Goiás State, Brazil.

Fig. 2. Astyanax goyanensis, UFRGS 11291, 59.2 mm SL. Scanning electronic microscopy images of the upper and lower jaws, left side, lateral view. Scale bar = 1 mm.

Fig. 3. Distribution of Astyanax goyanensis (circles) and A. courensis, new species (square), on upper rio Tocantins, Alto Paraíso de Goiás, Goiás State, Brazil. A, rio Tocantinzinho; B, rio Tocantins; C, rio Paranã; DF, Distrito Federal. Symbols can represent more than one lot or locality. Base map prepared by Marilyn Weitzman.

Fig. 4. (a) Rio dos Couros downstream from the Cachoeira São Bento, type-locality of Astyanax courensis, new species; (b) small stream tributary of rio dos Couros at Parque Portal da Chapada, locality of collection of Astyanax goyanensis.